Grabthar's Ruin

As told by Grathell, a duergar of the Unknown Lands. Items in italic are supposition.

Before the Fall (reference to the end of the Third Dynasty?), Grabthar was known as Giantsbane. She possessed a hammer that brought giants down with ease. When the overdynasty fell, Grabthar founded Xorn, a duergar city in the underdark. At some point after the city was founded, the great underwyrm appeared. It is a highly dangerous and destructive beast with claws of pure adamantine with a burrowing ability unrivaled by any other known creature. Grabthar took her hammer and her honor guard and went to defeat the underwyrm, but lost. The hammer was of little use against the underwyrm. Grabthar, the honor guard, and the hammer were all taken by the underwyrm for its horde. Fortunately, the underwyrm had been hurt badly enough that it found a new lair further away from Xorn and no longer troubled the city. Thus, Xorn was saved, even though Grabthar ultimately lost the battle against the great creature.

Her heroism inspired Xorn to adopt a new religious invocation: "BY GRABTHAR'S HAMMER!"